John Curl's Blowtorch preamplifier part II - Page 3114 - diyAudio
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Old 8th December 2012, 11:03 AM   #31131
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All this explain the two opposite tracks we can follow.
The John's one, using few components, paired, matched, sorted, in a no feedback configuration, for generating few distortions in themselves.
It is a long, difficult and expensive process, not industrial.
Or to use the quick'n dirty way, with similar results. Using average components in VERY fast closed loop feedback configurations.
Once the design is achieved, it is easily industrial and less expensive.

With the progress on the components speeds, the second way takes more and more advantages. Note than, talking about components distortions, in the John's position, they matters. In the second way, they are corrected by the feedback process.

In fact, i don't disagree with him, i just follow an other method to hit the same target :-)
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Old 8th December 2012, 11:03 AM   #31132
SY is offline SY  United States
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I note with amusement that the last time a blind test was arranged in this thread (it was testing phase response), not only did John refuse to try, he spent much effort trying to convince everyone else to not try as well. Despite his best efforts, several people DID try the test. At least one of the "scientists" got a perfect score, despite the proclamations of the ignorant that "scientists" say "everything sounds the same."

So really, Ricardo, why are you whipping on that dead horse? You're not getting the use of the Blowtorch, you know that.
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Old 8th December 2012, 11:08 AM   #31133
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Originally Posted by fas42 View Post
But ... have you tried doing that with the driver dead cold, and then compared that to the same unit after it's been installed in a carcase and driven hard for an hour or so with real music material, removed immediately and laid on the table again ...?

Frank
No. But the fact that the noise is there to the extent it is,
but yet unspecified, is pretty powerfull on its own.
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Old 8th December 2012, 11:12 AM   #31134
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Often we hear people accusing adiophools being in hallucination when they say they can hear differences. They believe that if the BT is properly controlled, they will not be able to hear differences between A and B. And they challenge these audiophools to a controlled blind test.

So my idea is to challenge these scientists to a blind test. May be they will learn something new. For example, if they think A is better than B because A has lower THD, then lets see if they can recognize which one is A.
I think you may be missing the point. The DBT challenge to 'audiophools' (your word) is simply to check if they can actually do what they claim to be able to do: distinguish items on (unsighted) sound alone.

The relevant test for 'scientists' would be: can you distinguish items by (unsighted) measurements alone?

It might then be amusing to swap over, as all scientists have ears and generally know how to use them but not all 'audiophools' have test equipment or know how to use it and properly interpret the results.
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Old 8th December 2012, 11:22 AM   #31135
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I would like to add a last philosophical word.
About numbers.
In the previous demonstrations, we have seen that numbers like slewrate have no absolute signification outside of their context.
Same thing about distortions, that everybody knows, todays, that they poorly reflect listening experiences. We have to know, in order to interpret those numbers, where and how.
Looking at numbers is a valuable approach for people which know how to figure-out their incidences in the ALL context.
There is NO contradiction between the scientific approach and the subjective (or artistic) one.
Both are about listening experience.
The scientific, on my point of view, require more previous knowledge, more learning time, but less time after, keeping you away to grope for a lot of things, taking apples for oranges.
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Last edited by Esperado; 8th December 2012 at 11:26 AM.
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Old 8th December 2012, 11:24 AM   #31136
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I think you may be missing the point. The DBT challenge to 'audiophools' (your word) is simply to check if they can actually do what they claim to be able to do: distinguish items on (unsighted) sound alone.

The relevant test for 'scientists' would be: can you distinguish items by (unsighted) measurements alone?

It might then be amusing to swap over, as all scientists have ears and generally know how to use them but not all 'audiophools' have test equipment or know how to use it and properly interpret the results.
No. We ALL know that $1 amp sounds different than $1000 amp. But when it is between $900 and $1000, some people start to ACCUSE others. The mission is to attack the person not the truth whether $900 and $1000 are different or not.

This accusation is simply based on the fact that these audiophools are really fools, don't know what they are doing, have no ability to measure distortions, etc. Not whether there is really differences.
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Old 8th December 2012, 11:25 AM   #31137
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It might then be amusing to swap over, as all scientists have ears and generally know how to use them but not all 'audiophools' have test equipment or know how to use it and properly interpret the results.
My words !
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Old 8th December 2012, 11:33 AM   #31138
Jay is offline Jay  Indonesia
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I would like to add a last philosophical word.

In the previous demonstrations, we have seen that numbers like slewrate have no absolute signification outside of their context.
Why is 1000V/us better than 60V/us? Is it audible (Talking about 50W or less)?

Last edited by Jay; 8th December 2012 at 11:35 AM.
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Old 8th December 2012, 11:39 AM   #31139
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Quote:
Originally Posted by Jay View Post
Why is 1000V/us better than 60V/us? Is it audible (Talking about 50W or less)?
Its not necessarily about the slew rate per se, rather higher slew rate correlates with better subjective impressions often (not always).

Take two opamps, with the slew rates you mentioned. The 1kV/uS is probably a CFB internally whereas the 60V/uS uses an LTP which is more RFI susceptible. Hence the former will probably sound better due to higher RFI resistance, but its SQ is nothing much to do with the slew rate number.
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Old 8th December 2012, 11:39 AM   #31140
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But when it is between $900 and $1000, some people start to ACCUSE others.
The question can be between 1000$ kits and 40 000$ prestigious ones.
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